Treatment of hydrocarbons



May 31, 1938. G, EGLQFF. 2,119,101

' TREATMENT OF HYDROCARBONS Filed July 31, 1957 Ea ctio nator Receh/r Patented May 31, 1938 PATENT OFFICE TREATMENT OF HYDROCARBONS Gustav Eglcil, Chicago, 111.. assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application July 31, 1937, Serial No. 156,745

2 Claims.

This invention relates to the treatment of hydrocarbon oils and refers more particularly to the conversion of relatively heavy hvdrocarbon oil fractions into lower boiling fractions of the nature of gasoline, kerosene and intermediate fractions by combined operations of cracking and hydrogenation.

More specifically the invention contemplates the cracking of hydrocarbon oils in a primary unit followed by hydrogenation of intermediate and heavy fractions and the return of the heavier of the hydrogenated fractions back to the cracking unit.

The cracking processis known to produce products having a greater degree of unsaturation than the charging oil so that there is a limit to the possible yields of lower boiling fractions on account. of the limited amounts of hydrogen available. This hydrogen deficiency not only fixes the yields of lower boiling fractions but also places limits upon the operatingfeatures'of cracking plants on account of tendency to deposit coke when too extensive dehydrogenation reactions are allowed to take place. It is one of the purposes of the present invention to permit the production of higher yields of low boiling products of better quality from the heavier portions of petroleums by a special combination of the operations pyrolysis and hydrogenation.

In one specific embodiment the present invention comprises subjecting hydrocarbon oils to conversion conditions of temperature and pressure, fractionating the cracked products toproduce gasoline and a plurality of intermediate fractions, hydrogenating the intermediate fractions to improve the quality thereof, fractionating said hydrogenated products to produce a plurality of condensates and recycling the heavier of said condensates to the primary cracking step.

To indicate the character of the process and the features of operation which characterize it, the attached drawing is provided which shows in general side elevation by the use of conventional figures an arrangement of interconnected units in which the process may be conducted. Referring to the drawing, charging stock which may comprise any of the heavier distillate or residual fractions of petroleums are admitted to a charging pump 3 by way of a line 1 containing a valve 2 and discharged through line 1 containing a valve 5 through a heating element 6 disposed to receive heat from a furnace l. Hydrogenated recycle stock, whose production will be described later, is admitted to line 6 by way of line 89. During passage through heating element 6 the temperatureof the combined feed is raised to a point within the approximate range of 900-1000 F. under superatmospheric pressures chosen to effect the best overall results in conjunction with the later hydrogenating steps. These pressures '5 may be of the order of 500 lbs. per sq. in. or higher as a general rule.

The cracked products pass through a 'line 8 containing valve 9 to a reaction chamber 10 which gives added time for completion of desired con- 10 version reactions and allows the separation of the heavier non-vaporized. cracked products which may be withdrawn from the bottom of the chamber through line containing valve 16 topump 19 for hydrogenating treatment or which may 15 be removed in whole or in part from the process by way of line 11 containing valve l8.- v

The vapors I from reaction chamber 10 pass through line H containing valve 1-2 to a fractionator 13 which is divided by intermediate plate i5 into upper and lower sections 14 and I6 respectively. The entering vapors are fractionated to produce an overhead gasoline, an intermediate side out fraction and a heavier distillate cut. The gasoline vapors pass through line I! containing valve 18 through a condenser 19 and the condensed vapors plus uncondensed gases pass through a line 20 containing valve 21 to receiver 22 which has a vent line 23 containing valve 24 for the release of the fixed gases and a line 25 containing a valve 26 for the release of the overhead gasoline to permanent storage.

An intermediate fraction accumulating on plate 15 at the bottom of the upper section of the fractionator is withdrawn through line 21 containing valve 28 to a pump 29 and discharged through a line 30 containing a valve 31 through a preliminary heating coil 32 disposed to receive heat from a furnace 33. Prior to'passage through heating element 32 hydrogen may be admitted 40 to line 30 from line H10 containing valve Hll to undergo preliminary heating prior to the hydrogenating step. If desired, the hydrogen necessary for the treatment of the intermediate fraction may be added after the heating element by 5 way of line 102 containing valve 103.

Hydrogen for the process isjadmitted by way of line 91 and valve 92 to compressor 93 which discharges through line 94 containing a valve 95 through a heating element 96 arranged in a furnace 91, the preheated hydrogen passing through line 98 and valve 99 to line 106 or to lines I04 and 111 as will be presently described; The hydrogen need not be entirely pure although it is preferably free from excessive quantities of ma- 5 terials which will poison the hydrogenating catalysts.

The mixture of hydrogen and intermediate products from heating element 32, at a temperature and under a pressure found to be optimum for effecting the desired degree of hydrogenation, pass through line 34 containing a valve 35 to a reaction chamber 36 which preferably contains catalysts comprising such materials as iron, nickel, cobalt, chromium, molybdenum, etc. and/or their oxides or sulfides either alone or in combination, the catalysts being chosen with regard to the degree of hydrogenation desired and the presence of possible contaminating materials such as hydrogen'sulfide or organic sulfur compounds. Line 82 containing valve 83 is provided as a draw line at the bottom of reaction chamber 36 to remove any liquid accumulations from the catalyst chamber. The vapors from the chamber plus any excess of hydrogen or other fixed gases pass through line 31 containing valve 38 to a fractionator 39 where they undergo fractionation with other hydrogenated material whose source will be presently described.

Line 59 containing valve 60 is provided at the bottom of fractionator l3 to remove heavy in.- termediate fractions and transfer them to pump 83 while branch line 6| containing valve 62 permits the withdrawal of all or a portion of these fractions from the process at this point. Pump 63 discharges through line 64 containing valve 65 to line 66 containing valve 61 and leading to heating element 68 arranged in furnace 89. Hydrogen may be admitted from line I04 containing valve I05 to undergo heating and mixing with the heavier intermediate fractions during passage through the heating element or the hydrogen may be admitted after the passage of the intermediate fraction by the use of valve I06.

The hydrogen and heavier intermediates from coil 68 pass through line 10 containing valve II to a separate reaction chamber 12 which preferably contains hydrogenating catalystsslmilar to those used in chamber 36 although the nature of these catalysts may be varied to suit the particular requirements of the heavier intermediates. As before, a lower draw line 84 containing valve 85 is provided for the removal of any liquid condensates accumulating at this point. The hydrogenated products plus any excess of hydrogen or other fixed gases pass through line 13 containing valve 14 to line 31 and thence to fractionator 39.

In general the temperatures employed in the hydrogenating zones will vary from approximately 500-800 F. while pressures are varied between the approximate ranges of 500-3000 lbs. per square inch. The temperature employed will be lower as the boiling points of the fractions treated are lower and the pressures will be higher.

The reasons for this are that the lighter are in general more olefinic and hydrogenatable at low- .er temperatures while the higher fractions are relatively more cyclic and require higher temperatures for the eifective addition of hydrogen, particularly when it is desired to open the rings to produce, open chain or paramnic hydrocarbons.

The invention further comprises the hydrogenating treatment of liquid residual material separating in the primary cracking reaction chamber l0 which is drawn from the chamber through line 15 and valve I6 as already described and which is preferably taken by a pump 19 and discharged through a line 80 containing valve 8| into line 64 to undergo hydrogenation along with the heavy intermediate fraction taken from the bottom of a fractionator l3. The proportioning of heavy residuum and heavy intermediate fractionator bottoms will depend upon the character of the primary charge to the process and the character of the products desired. Similarly the conditions of hydrogenation in the secondary unit for the heavier stocks will be varied to produce the best overall results.

The combined products entering fractionator 39 are now preferably split up into fixed gases, overhead motor fuel fractions, intermediate refined stocks, and recycle material for return to the primary cracking unit for further conversion along with the original charge. As shown in the drawing, fractionator 39 is divided into compartments 40, 42, and 44 by means of capped plates 4| and 43 from which intermediate fractions may be drawn through line 45 containing valve 46 and line 41 containing valve 48 respectively. Low boiling overhead fractions comprising unreacted hydrogen, other fixed gases and vapors of gasoline boiling range produced incidental to the hydrogenating operations pass through line 49 containing valve 50 through a condenser 5| from whence the condensed liquids and fixed gases pass through a line 52 containing valve 53 to a receiver 54 provided with a fixed gas release line 55 containing valve 56 and a liquid line 51 containing valve 58 for the removal of overhead gasoline fractions.

The heavy bottom fractions from fractionator 39 are now preferably returned to the cracking stage by way of line 86 containing valve 8'! and recycling pump 88 which discharges through line 89 containing valve 90 back to line 4. This type of operation makes a very desirable recycle stock since its hydrogen content is sufiicient to permit cracking under severe conditions with production ofkhigh yields of gasoline and small amounts of co e.

As an example of the results obtainable by an operation falling within the scope of the invention a 26 gravity topped crudefrom the Mid-Continent producing area may be cracked in the primary unit at a temperature of 940 F. and 300 lbs. pressure to produce 45% of 53 gravity intermediate fraction and 30% of 20 gravity residuum. In succeeding hydrogenating units the intermediate fraction and residuum may be separately treated to produce more highly saturated and refined products. The 35 gravity intermediate fraction may be hydrogenated at pressures of approximately 1800 lbs. per square inch and temperatures of approximately 700 F. to produce therefrom 75% of 40 gravity finished kerosene with attendant production of 10% of low boiling fractions suitable for use as gasoline. The 20 gravity residuum may be processed at pressures of approximately 750 F. to produce a yield of lubricating oil stock of 25 gravity, with the incidental production of 15% of hydrocarbons of gasoline boiling point range and 5% of hydrocarbons boiling within the range of kerosene. By returning the heavy hydrogenated products from the final fractionator to the primary cracking element the production of gasoline in the cracking step is increased to 55% of the charge.

I claim as my invention:

1. In the conversion of hydrocarbon oils heavier than gasoline into more valuable products, the method which comprises cracking the oil and separating therefrom at least two fractions of different boiling points, hydrogenating the lighter of said fractions by subjection to hydrogenating conditions of temperature and pressure, independently hydrogenating the heavier of said fractions at higher temperature and under lower pressure than the lighter fraction, combining the vapors formed by the independent hydrogenation of said fractions, fractionally condensing the resultant vaporous mixture to form a plurality of condensates, and recycling the heavier of said condensates to the cracking step.

2. In the conversion of hydrocarbon oils heavier than gasoline into more valuable products, the method which comprises cracking the oil and separating the same into vapors and unvaporlaed oil, fractionating the vapors to form a light fraction and a heavier fraction, combining the heavier fraction with the unvaporized oil and hydrogenating the resultant mixture by subjection to hydrogenating conditions of temperature and pressure, independently hydrogenating said light fraction at lower temperature and under higher pressure than said mixture, combining the vapors formed by these independent hydrogenating treatments and iractionally condensing, the resultant mixture to form a plurality of condensates, and recycling the heavier of said condensates to the cracking step.

GUSTAV EGLOFF. 

